Our objectives are to evaluate the stability of the cellular mechanisms for the regulation of enzyme accumulation during the process of biological aging. We wish to determine if the accumulation of catalytically incompetent enzyme forms in senescent organisms occurs as a consequence of age-dependent alterations in protein turnover. We will use the free-living nematode, Turbatrix aceti, as a model system for these ageing studies. Available evidence obtained with this system indicates that the rate of degradation of nematode enolase, an enzyme which undergoes age-related structural modification, is severely impaired in aging animals, as is the rate of protein turnover in general. In this connection, we will continue to examine the turnover characteristics of "altered" enzymes in young and old nematodes, as well as in young and senescent Fischer 344 rats. Results will be compared with degradation half-lives determined for "unaltered" enzymes in an effort to explain why some enzymes accumulate aberrant forms in senescent cells, while others do not. We consider it probable that the pronounced slowing of protein degradation in aging nematodes results from a partially dysfunctional protein degradative system. In this regard, we have identified two families of proteinases in T. aceti, one active in the acid region and the other in the alkaline pH range. We propose to isolate and characterize these proteases, to determine their subcellular location, and to investigate their possible roles in nematode protein catabolism and aging.